How To Check Power Supply Wattage Without Opening Computer?

Understanding what power supply unit you have and its wattage is essential for any PC builder particularly if you are planning on adding new power hungry components like a graphics card to your PC.

But for those of us who do not want to go through hassle of disassembling our PCs, is there a reliable way on how to check power supply wattage without opening the PC?

Unfortunately, the answer to that question is generally a no. There is only one way, but for that you need to know the serial or the model number of your PC. I will discuss this method below. Other than that, to check your PSU wattage, you will HAVE to perform minor disassembly of your PC case, which is often quite easy though.

In the text below, I will talk in detail regarding how you can check your PSU wattage rating either without opening the PC at all or with just a slight disassembly.

How To Check Power Supply Wattage Without Opening Computer?

As mentioned earlier, there aren’t a whole lot of ways to determine what Power Supply Unit you have or its wattage without some sort of disassembly.

But I will discuss two easy methods below:

  1. Check Out Your Desktop’s Specsheet Online For PSU Wattage
  2. Check Out the Labels on The Power Supply Unit

1. Check Out Your Desktop’s Specsheet Online for PSU Wattage

The only non-invasive way to check your desktop’s power supply wattage without opening it is through its specsheet.

There are two scenarios here:

  1. You bought a prebuilt PC, hence you will need to check its make and model or serial number
  2. You made a desktop build yourself. You will have no serial number or model name in this case

Scenario 1: You Bought a Prebuilt PC

If you bought a prebuilt PC from a brand like Dell, Acer, Asus, Lenovo, HP etc, then it should have a model or a serial number.

You can often find the model or the serial number of your prebuilt desktop through a tag/label located on your desktop’s case.

How To Check Power Supply Wattage Without Opening
Serial Number / Label Tag on Dell Desktop. Source: Dell

The label can be found anywhere. It can be at the back of the chassis, on top of the chassis or underneath.

The label often has both the serial number as well as the model number clearly indicated.

Once you have found the serial number or the model number, you can do one of two things. You can either call the manufacturer on the helpline and ask them regarding the wattage of the PSU in your PC, or you can check its specsheet online. 

Lets take Dell Inspiron 3880 Desktop for instance. So if you have this make and model of desktop you can head over to its specifications on the official website and check out its Power Supply Unit Wattage Ratings.

Power Supply Unit Specs for Dell Inspiron
Power Supply Unit Specs for Dell Inspiron 3880

As you can see from the technical specs above, Dell Inspiron 3880 either has 200W or 260W PSU. This should give you a solid insight into whether your PSU is sufficient for adding more components or not.

Scenario 2: You Made a Desktop Build Yourself

If you assembled a desktop PC yourself by buying all the components yourself. Or if you bought a PC which was assembled by a third party vendor, then there isn’t whole lot you can do to check the PSU wattage without some sort of disassembly

You can, however, refer to your old receipts to check the model name of the PSU or ask the the third party vendor regarding the details of your PC build.

2. Check Out the Labels on The Power Supply Unit

The second way to figure out the wattage of your Power Supply unit requires a little disassembly. This method is a slightly tedious but the it can give you the most definitive answer to the wattage question. 

Rest assured, though, this method does not require you to take any parts or plugs out. All you need to is remove the side panel of your desktop case.

remove the side panel cpu case
Remove the Side Panel to get access to your PSU label/tag.

Once the side panel is removed, check for the specs sticker/label on the Power Supply Unit itself. A majority of the power supply units have the specifications label on them. This label can be located in any of the sides of the PSU.

Power Supply Unit Label Rating jpg
Power Supply Unit Label

From this rating label I can not only see the model number (Gigabyte GE M800A, but also see the max wattage rating which is 800W in this case.

Also Read: How to Check if RAM is Dual Channel?


Can You Use Power Meter or Multimeter to Check Power Supply Wattage Rating?

No, you cannot use Power Meter or a Multimeter to check the PSU wattage rating. 

The Power Meter or a multimeter can only tell you the power BEING DRAWN. It does NOT tell you the MAXIMUM or the rated power of the Power Supply Unit.

In other words, if I have an 800W power supply, but if my components are using only 300W, then the Power Meter or the multimeter will show the reading as 300W, NOT 800W.

The power drawn is affected by many factors including what components you have as well as the task you are performing. Gaming, for instance, draws more power as compared to word processing since with gaming the CPU and the GPU ramp up their voltage/clockspeed and thus increasing their performance and power draw.

Can You Check Power Supply Unit Wattage in Windows?

Unfortunately, you cannot check the wattage rating of your PSU within the operating system. 

Also Read: How to Check RAM Type in Windows 10?

Final Words

So again, there aren’t whole lot of ways on how to check power supply wattage without opening your PC case.

But fortunately, checking your PSU rating isn’t tedious. All it requires is for you is to remove the side panel. 

let me know if you know of any other non-invasive ways of checking the PSU wattage rating. 

Categories PSU
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Atif Qazi
Atif Qazi is the founder of PCGuide101 and an expert in the computer peripheral industry with over two decades of experience. He has worked as a consultant for major companies and has a deep understanding of the inner workings of computer peripherals. He has a degree in Electrical Engineering and has served as a product manager and technical consultant. He is passionate about testing and evaluating the latest products to provide readers with reliable information.

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